After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?


--
Simon Elliott http://www.ctsn.co.uk

Simon Elliott was thinking very hard :
Is there anything I can do with this valve without draining the whole
system?

Just a suggestion with no idea of its worth....

Could you try turning the valve down at the other end of the rad to
reduce the flow a little - that might prevent the clunking.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 23/11/2005, Harry Bloomfield wrote:

Just a suggestion with no idea of its worth....

Could you try turning the valve down at the other end of the rad to
reduce the flow a little - that might prevent the clunking.

Interesting idea! I'll give it a try when/if the problem recurs.


--
Simon Elliott http://www.ctsn.co.uk

"Simon Elliott" Simon at ctsn.co.uk wrote in message
.. .
After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?

An old chestnut reply is to ask if the valve is fitted the right way round
for the water flow. Older TRV's will rattle if the flow is backward, these
should have an arrow or indicator to show the correct flow direction. Some
newer valves are bidirectional

bland

Funny enough I'm having a similar problem.

I had 90% of my central heating system re-plumbed recently, the other
10% was replaced a couple of years ago. When the Boiler starts up I
hear a tinkering from some of the valves, it something to do with the
flow of water - turning the valve down reduces the noise. I haven't had
some time to investigate.

"Simon Elliott" Simon at ctsn.co.uk wrote in message
.. .
After a new boiler was installed, our CH system started knocking after
it had been running for a while. Turning the thermostat on the hot
water cylinder up higher would make the knocking stop for a while. The
guys who did the installation tried turning the pump speed down, which
helped a bit but didn't fully solve the problem.

The chap who came round to service the boiler suggested that it might
be washer flutter in one of the thermostatic valves. Today being a cold
day, the knocking started again. I went around the radiators with
thermostatic valves, and found one which seemed noisy. Turning the
valve slightly stopped the noise. Playing with the valve, it seemed to
be quite clunky.

Is there anything I can do with this valve without draining the whole
system?

Yes - leave the valve fully on or fully off.

I have the same problem, since installing a new boiler. I suspect one or two
valves were put in the wrong way around, but it did not cause a problem with
the old pump. The new pump more powerful and so is causing the valve to
knock. Next time the system is emptied, I'll turn the valves around, but in
the meantime, leaving a few valves fully on is not too big a problem.

-- JJ

On 23/11/2005, bland wrote:


An old chestnut reply is to ask if the valve is fitted the right way
round for the water flow. Older TRV's will rattle if the flow is
backward, these should have an arrow or indicator to show the
correct flow direction. Some newer valves are bidirectional

I think you've hit the nail on the head. I assume that the water is
flowing from the hotter radiator pipe to the cooler one, and if so,
it's fitted back to front. Looks like I'll need to wait till the next
time I want to drain the system.


--
Simon Elliott http://www.ctsn.co.uk

In article ,
Simon Elliott Simon at ctsn.co.uk wrote:
Today being a cold day, the knocking started again. I went around the
radiators with thermostatic valves, and found one which seemed noisy.
Turning the valve slightly stopped the noise. Playing with the valve, it
seemed to be quite clunky.

Some TRVs can only be fitted on (usually) the flow side. They'll often
have an arrow on them denoting direction of flow. Fitting them on the
return can give the symptoms you describe. So check by seeing which pipe
gets hot from cold first - this will be the flow.

--
*I'm not being rude. You're just insignificant

Dave Plowman London SW
To e-mail, change noise into sound.